1. Technical Field
The present disclosure relates to a slave module for monitoring an electric system.
2. Description of the Related Art
Electronic devices installed in substations, power stations, etc. measure and monitor the operation state and the quantity of electricity of a variety of devices used in switchgears. In addition, the electronic devices installed in substations, power stations, etc. may perform protection function including shutting off a line in case of an accident as well as control function.
To efficiently operate an electric system, an electronic device incorporated in a power device is operated in such a manner that a master module sends request data to a slave module, and then the slave module sends response data in response to the request data. When an abnormal situation takes place in the system or a device or when a fault occurs in a system line, such functionality provides important information for determining the order that all information is generated and for determining the cause of the fault.
In particular, when a fault such as grounding, overload, short-circuit, etc. takes place in a line of a power system, the fault prevails instantly such that all power installations in the system may be affected. Therefore, when a fault such as grounding, overload, short-circuit, etc. takes place in a line of a power system, it is necessary to quickly transmit such data to the master module to repair the fault.
FIG. 1 is a diagram showing existing slave modules 11, 12 and 13 for monitoring an electric system and an existing master module 20 connected thereto via a serial bus. The operation of the existing slave modules 11, 12 and 13 and the existing master module 20, and the problems will be described in detail below with reference to FIG. 1.
Initially, the master module 20 sends request data to the slave modules 11, 12 and 13 via the serial bus. Then, the slave modules 11, 12 and 13 send response data via the serial bus only when they receive the request data. The request data and the response data are transmitted/received in a so-called round-robin scheme, i.e., repeatedly in the order that the slave modules 11, 12 and 13 are arranged.
In the existing round-robin scheme, however, it is not possible to determine whether there is a carrier in the serial bus, and thus collision between data may occur. In addition, in the existing round-robin scheme, as data is transmitted/received in the order that the slave modules 11, 12 and 13 are arranged, when emergency data is generated, it cannot be transmitted first. Moreover, in the existing round-robin scheme, as the slave modules 11, 12 and 13 send response data only when they have received request data, it takes a long time for the master module 20 to acquire data.